Semi-Transparent JPEG image

I have Photoshop CS2, and I'm looking to make a jpg/jpeg image to texture a VRML model with - The graphic needs to be semi-transparent, as I need the nurb's Material color to show through it. I appreciate that a png image would offer a solution to this problem instantly, but this format is not usable in the situation offered... On the same note, gif format is also out of the equation because it offers only transparency, or no transparency.

If you look at this image ChromeBall.jpg it is exactly what I'm looking to achieve (but not with this image). When I add levels of opacity to the jpg image I want to be semi-transparent, the background of the image shows up as being 'white' whether I save as, or save for web.

Help if you can, please!

I...don't understand what you want. You want your image, when you save it, to be part-transparent? Ddi you try saving it as .png? I'm not sure if itll make a difference, but...

JPEGs can not be transparent at all. It is not possible with that format. You'll have to use PNG or some other method of making it transparent.

Thanks for the responses, guys... but;

Koolstr - like I stated in my initial post, in this situation, PNG format cannot be used as the image I want to be 'semi-transparent' needs to be around 20kb's filesize-wise, which I wouldn't get even close to in PNG format.

deker - In this situation, a JPEG/JPG graphic can be semi-transparent. The image I posted shows on any 3D nurb, and the nurb's own material color will show 'through' it as if the white in the image doesn't exist, so to speak. I would post an example, but I am sure few or none of you have a 3D Client installed on your PC's, so it would be a fruitless task.

But than it isn't a JPEG setting but a setting in the 3D client.
It probably works the same as the opacity slider in photoshop?

Like Derek said, it's not possible to create a transparent JPEG. see: http://www.faqs.org/faqs/jpeg-faq/part1/section-12.html